Dual-Polarization Absorptive/Transmissive Frequency Selective Surface Based on Tripole Elements

This letter presents an absorptive/transmissive frequency selective surface (ATFSS) with wide absorption bands at both sides of a passband. A double-layer structure consisting of a lossy FSS and a lossless FSS was employed. The lossy and lossless FSSs were designed based on tripole loops and tripole slots, respectively. The tripole loops and slots were constructed as a hexagonal periodic structure. The tripole loops equated to a series-parallel circuit and exhibited lossy feature after they were loaded with lumped resistors, which were used to absorb the incident wave at lower and upper absorption bands. Surface current distributions were illustrated to explain the operation mechanism. A prototype of the proposed ATFSS was fabricated and measured. Our results showed good agreement between measurements and simulations. Measurement results showed that a passband with a center frequency of 5 GHz and a minimum insertion loss of 0.35 dB was obtained. Out of the passband, absorption rates higher than 80% were obtained at a lower absorption band, from 2.66 to 4.5 GHz, and at a higher absorption band, from 5.66 to 8.56 GHz.